diff --git a/src/cas/build/singleThread/Makefile.Host b/src/cas/build/singleThread/Makefile.Host
index 84d0e8661..42dd86d6b 100644
--- a/src/cas/build/singleThread/Makefile.Host
+++ b/src/cas/build/singleThread/Makefile.Host
@@ -38,11 +38,11 @@ LIBSRCS += casAsyncAtIOI.cc
 LIBSRCS += casEventSys.cc
 LIBSRCS += casMonitor.cc
 LIBSRCS += casMonEvent.cc
-LIBSRCS += inBuf.o 
+LIBSRCS += inBuf.cc
 LIBSRCS += outBuf.cc
-LIBSRCS += dgInBuf.o 
+LIBSRCS += dgInBuf.cc 
 LIBSRCS += dgOutBuf.cc
-LIBSRCS += casCtx.o 
+LIBSRCS += casCtx.cc 
 LIBSRCS += casEventMask.cc
 LIBSRCS += ioBlocked.cc